Method and apparatus for combination weighing

ABSTRACT

A weighing system for making a predetermined weight of a product comprised of individual articles having variable weights by selecting the product stored in a combination of a predetermined number of storage cups. Quantities of the product having targeted weights are distributed to a plurality of scale-controlled hoppers for accurate weighing. The weighed product is fed from each of the scale-controlled hoppers to a plurality of storage cups associated with each of the hoppers, and the product weight associated with each storage cup is registered. Specific combinations of storage cups are tested to determine whether the combined product weights therein add to make the desired weight, within acceptable limits. The first combination found to make the weight is used, and the appropriate storage cups are emptied to a container for receiving the product. The appropriate storage cups are refilled from the scale, and the process repeats. When none of the combinations of the preselected number of storage cups include a total product weight within the acceptable limits, the limits are broadened and the cycle repeats. The weighing system includes a programmed microprocessor for controlling operation thereof, for providing the combination to be tested, for calculating the combined weights, and for determining whether the combined weight falls within the acceptable limits. A specific distributor for the product includes a reversing rotating portion for preventing clogging of the product at openings provided for chutes connecting the distributor to the scale-controlled hoppers.

TECHNICAL FIELD

The present invention relates to the field of weighing systems, and moreparticularly to a method and apparatus for making a predetermined weightof a product, comprised of a plurality of articles having widely varyingweights, by selecting a combination of weighed quantities of the productfrom storage cups therefor.

BACKGROUND ART

In the weighing art, it is known to obtain a precise weight of a productformed of a plurality of individual articles having various weights,each of which is a significant fraction of the total desired weight, bythe use of "combination weighing devices". Such devices are disclosed,for example, in U.S. Pat. No. 3,939,928 to Murakami et al, and in U.S.Pat. No. 4,267,894 to Hirano et al.

In the Murakami et al patent a number of objects are fed to each of aplurality of weighing hoppers. A complicated electronic circuit is usedto test successive combinations of hoppers for a combined weight lowerthan the previously achieved best weight. The circuit thus ultimatelyprovides a combination having a weight whose deviation from the desiredweight is minimal over all possible combinations of hoppers. Objectsfrom the appropriately selected hoppers are delivered to a pool hopper,from whence the objects are discharged to be collected in a bucket. In aparticular example, eight weighing machines are used, and a singleobject is loaded into each such weighing machine. A total of 154combinations of hoppers for the weighing machines are tested by limitingthe number of objects to be taken out to be 4, 5 or 6.

In the Hirano et al improvement on the '928 teaching, a predeterminednumber of articles is loaded into each of the weighing balancesprovided. An adding circuit receives as a negative input the intendedweight to be obtained, and positive inputs from each of a plurality ofholding circuits storing the weights in the balances. A combinationgenerator is provided for gating the outputs of sequential combinationsof balances to the adder. The output of the adder is compared with upperand lower deviation limits for the intended weight. If the output of theadder is within the accepted deviation, the selected combination isstored in a combination memory and the adder output used to update theacceptable upper limit of the intended weight. That is, each combinationof balances determined to have an acceptable product weight is used tonarrow the acceptable deviation limits, thereby arriving at acombination storing the weight closest to the intended weight.

As is apparent from the above summaries, the prior art generatessubstantially all combinations of balances or hoppers to test allcombinations of weights against the desired weight. Such generation isinefficient, and arises particularly from the fact that the itemsprovided into the balances, or weighing hoppers, are not in themselvespreweighed. Further, by seeking the best combination of hoppers,needless time is wasted in comparison of the repetitive combinationswhen an acceptable combination may have already been found. Stillfurther, such prior art approaches provide no solution for the problemarising when none of the tested combinations meets the acceptabledeviation from the desired weight. The prior disclosures further sufferfrom the deficiency of inefficient use of scale and weighing apparatus,in which several scales are each used to provide the product to but asingle hopper. The weighing devices remain idle during most of theoperation of such combination weighers.

There is thus a need for a combination weighing device having simplifiedelectronic circuitry which generates combinations of only apredetermined number of storage cups, rather than of all possiblecombinations of storage cups, for more rapidly reaching a decision as toacceptable combinations. Additionally, a combination weighing apparatushaving simplified circuitry for rapidly determining an acceptablecombination is needed, as well as such a system in which weighingdevices are efficiently used.

DISCLOSURE OF INVENTION

It is accordingly an object of the present invention to provide acombination weighing system overcoming the difficulties of the priorart.

It is a more specific object of the present invention to provide acombination weighing system, and a method of operation therefor, capableof quickly reaching a decision as to a combination of storage cups to beused to make a desired weight of a dry flowing product.

It is another object of the invention to provide a combination weighingsystem having a plurality of storage cups associated with each weighingscale used therein, thereby to provide more efficient usage of theweighing scales.

It still another object of the invention to provide a combinationweighing system wherein a product is distributed to a plurality of scalehoppers in quantities having targeted means weights, thereby to enableselection of combinations of the contents of a predetermined number ofstorage cups to make the desired weight.

Yet another object of the invention is the provision of a combinationweighing system in which the first combination of storage cups having acombined product weight meeting the desired weight within acceptablelimits is selected for making the weight.

It is an additional object of the invention to provide a combinationweighing system in which certain combinations of storage cups aredetermined to be favorable over other combinations, and in which thefavorable combinations are tested prior to testing of the othercombinations.

It is still a further object of the invention to provide a combinationweighing system in which a number of combinations of storage cups aretested for making up a desired weight within an acceptable weight range,and in which the acceptable weight range is broadened if the testedcombinations fail to make the desired weight within the initiallyacceptable range.

To achieve the foregoing and other objects, and in accordance with thepurpose of the present invention as embodied and broadly describedherein, a combination weighing system is described including a pluralityof scales and associated hoppers. A distributor is provided todistribute quantities of the product to be weighed to the various scalesand associated hoppers. Each scale and hopper has associated therewith aplurality of storage cups for receiving the product therefrom. A controlsystem is included in which various components are provided forestablishing acceptable upper and lower limits for a range of productweights to be achieved, for registering the weight or products stored ineach of the storage cups, for providing combinations of storage cups andfor calculating the total product weight in these combinations. Finally,a selector is provided within the control system for selecting the firstcombination of storage cups having a combined product weight within theestablished, acceptable weight range and for signaling the acceptance ofthe combination and the need for provision of new combinations formaking the next desired weight.

In accordance with a further feature of the invention, the controlsystem includes a cycling component for providing a signal indicative ofa failure of all combinations of storage cups to provide a weightmatching the desired weight within the acceptable limits. The limitsetting component is responsive to that signal by broadening theacceptable range, and by initiating a further cycle of operation of themachine.

In accordance with one aspect of the invention, the control systemincludes a programmed microprocessor which forms the various componentsthereof. The programmed microprocessor further includes a dividingcomponent for forming a first fraction whose denominator is determinedby the predetermined number of storage cups to be used in thecombinations to be tested. The numerator of the fraction is determinedby the desired product weight, and the fraction so formed is provided tothe various scales as a target mean weight to be provided to the hopperand the storage cups associated therewith. In accordance with anotherfeature of the invention, the fraction formed by the divider of themicroprocessor is varied to provide second and third fractions offsetabove and below the first fraction. The offset values are provided toseveral of the scales, thus targeting some of the scales to receivequantities of the product having a mean weight above the first fraction,and targeting others of the scales to receive quantities of the producthaving a mean weight below the first fraction.

In accordance with yet another aspect of the invention, the distributorfor the product includes a frame having an aperture for receiving theproduct, and a rotator within the frame for dispensing the product toeach of the scale-hopper combinations. Control means are provided foralternately causing the rotator to rotate in a first direction and in asecond, opposite direction. More specifically, the control means causesthe rotator to rotate in the first direction for a greater period oftime than in the second direction.

Still more specifically, the control means includes an eccentric primemover, a pivoted arm connected to the rotator, and a linkage connectingthe prime mover to the pivoted arm. Additionally, a clutch iselectrically controlled for selectively engaging and disengaging thepivoted arm from a shaft connected for rotating the rotator.

In accordance with still another aspect of the invention, a method isprovided for making up the desired weight of a product by using theapparatus described above. Thus, acceptable upper and lower limits foran acceptable range of product weight are established. Quantities of theproduct are distributed to the plurality of scale-hoppers, thedistribution of the product to any particular hopper terminating upon adetermination by the scale that a predetermined weight has beendistributed thereto. The product is fed from each of the hoppers to oneof the storage cups associated therewith, and the weight stored in thestorage cup is then registered. Various combinations of the registeredweights are calculated, and a combination of storage cups having a totalproduct weight within the established acceptable limits is selected tomake the desired weight.

The present invention more particularly provides for selecting the firstcombination of storage cups having a total weight within the establishedacceptable limits.

In order to provide more efficient utilization of the scale weighingsystems, the combinations of storage cups tested are ordered to favorselection of combinations involving storage cups associated withdifferent weighing scales. The combinations may also be arranged in anorder in which combinations are favored which involve storage cupsassociated with scales which did not have storage cups associatedtherewith forming a selected combination in an immediately previouscycle.

In accordance with a significant aspect of the invention, when none ofthe tested combinations makes the desired weight within the acceptablelimits, the acceptable limits are changed to broaden the permittedrange. The cycle is then repeated to select a combination of storagecups having a total product weight falling within the broadenedacceptable limits.

The foregoing and other objects, features and advantages of the presentinvention will become more readily apparent to those skilled in the artfrom the following description wherein there is shown a preferredembodiment of the best mode for carrying out the invention, simply byway of illustration and not of limitation of the invention.

BRIEF DESCRIPTION OF THE DRAWING

The preferred embodiment of the invention will be understood from thefollowing description when taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 schematically illustrates the preferred embodiment of theinvention and the principles thereof;

FIG. 2 illustrates schematically a control system for the embodiment ofFIG. 1; and

FIG. 3 shows a flow chart for use in another form of the control systemof FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to FIG. 1, an apparatus embodying the principles of theinvention is shown for making a desired weight of a solid fluid product,such as food products of various types. The apparatus may be used, forexample, to make up desired weights of extruded snacks, potato chips,pretzels, candies or the like for packaging in a package, such as apillow-type bag.

Devices for filling the product into the package, for forming the bags,or the like, which may be used with the present invention, do not form apart of the invention, however.

As shown in the Figure, a product distributor, shown generally at 10,may include a dispensing apparatus 12 similar to that described in U.S.Pat. No. 3,710,980 to Henry, assigned to the assignee hereof. In such adispensing apparatus, a distributor 14 with vertically oriented walls isprovided with an opening for receiving the product to be dispensed. Thespecific location of the opening may be varied to accommodate differentfeeding devices. In the present embodiment, it is contemplated to havean opening at the top for dropping the product into the distributor 14.

A conical member 16 is rotatably disposed within distributor 14 todispense the product through a plurality of openings provided in theperipheral structure of the distributor. Two such openings aresymbolically shown at 18 and 20. Preferably, conical member 16 isprovided with longitudinal ribs, symbolically shown at 22, forfrictionally rotating the product within the distributor.

Product dispensed by apparatus 12 is provided through openings 18 and 20to a plurality of product conveying, or feeding, devices illustrativelyshown at 24 and 26, for example. The conveying devices may be similar tothe vibratory conveyors shown in U.S. Pat. No. 3,578,094 to Henry et al.and assigned to the assignee hereof. Such a device may include an outletchute 28 and a vibrator motor 30.

As further shown in the figure, each conveyor provides the product to ascale hopper, shown at 32 and 34. The weight of product provided tohoppers 32 and 34 is monitored by scales 36 and 38 which provideelectrical signals representative of the provided weight. Scales 36 and38 are symbolically shown as mechanically linked to their respectivehoppers by mechanical linkages 40 and 42, although it is to beunderstood that the scales may be integrally connected to the hoppers.

The scales form a feedback system in conjunction with the associatedhoppers and vibratory conveyors provided therefor. One such feedbackscale known to those skilled in the art is sold under the designation"Clipper 713S" manufactured by The Woodman Co. Inc., assignee of thepresent invention. The scales 36, 38 of the weighing system control thefeeders 24 and 26 to provide particular weights of the product tohoppers 32 and 34. The specific weights to be provided to the scalehoppers are determined by a control system 44. The control system 44 isin two way electrical communication with scales 36 and 38 over two wayelectrical communication paths 46 and 48, respectively. Thus, thecontrol system receives information from the scales pertaining to theweight of product provided to the associated hoppers, and furtherprovides information to the scales as to the targeted mean weight forthe product to be dispensed thereto. Scales 36 and 38, responsive to thetargeted mean weights provided thereto by control system 44, thusprovide signals along paths 49 and 51 to the vibrators associated withthe particular feeding devices therefor. The scales thus terminatefeeding of the product to hoppers 32 and 34 when a predetermined weightof the product has been detected therein.

It should be understood that other control devices may be used forcontrolling the quantity of product dispensed to the hoppers. Forexample, the drum 14 may discharge the product directly into the scalehoppers through controllable doors. The scales associated with thehoppers may provide the control signals for closing the respective doorsonce the appropriate quantity of product is dispensed.

In the preferred embodiment, however, vibratory feeding devices areused. It should be recognized that once the feeding devices are stoppedunder control of scales 36 or 38, the solid product accumulates atopenings 18 and 20, thereby preventing further product discharge to thechutes.

It is thus seen that targeted weights of product may be provided to aplurality of scale hoppers distributed about the product distributor. Aswill be appreciated by those skilled in the art, the weights accumulatedin each of the hoppers can be targeted for a desired value, but willactually provide variations about a mean which approximates such adesired value. This is due to the fact that the desired weight is afinite multiple of the weight of each object in the product. Forexample, in packaging pretzels where each pretzel may typically provideapproximately five percent of the packaged weight, a single pretzel mayvary from three to eight percent of the total weight to be made. Thus,although the actual weight of product within the hoppers is below thetargeted weight, provision of an additional object may raise the weightto a value above the targeted weight.

Combination weighing devices of the prior art provide for approximatinga total weight to be made by combining the weight of some subset ofproduct quantities. The present invention advances over the prior art,inter alia, by targeting specific weights for the quantities to form thesubsets.

That is, in accordance with the present invention a number of scales andassociated hoppers are provided. The illustration of FIG. 1 shows twosuch scales, but it is to be understood that any number may be provided.In one example, eight scales are provided. If each scale is providedwith a targeted weight of one third of the total weight to be made, itis understood that only combinations of three hoppers need be tested tomake up the product weight to be packaged. Prior art devices, asdescribed previously, do not provide such target weights to the hoppersto be tested, and accordingly must test all combinations of any numberof hoppers in order to make the desired weight. A further advance of thepresent invention includes the targeting of some of the scales toreceive a weight offset from the fraction of weight to be made by apredetermined positive amount, and targeting others to receive a weightoffset from the fraction of the desired weight by a negative amount.This approach increases the likelihood that a combination of weightswill be found, some above and some below the targeted fraction of theweight to be made, which combine to provide the desired weight to bemade.

In accordance with yet another feature of the invention, each scalehopper is provided with a plurality of associated storage cups. Thus,hopper 34 is provided with associated storage cups 50 and 52, forexample.

By providing a plurality of storage cups for the hopper associated witheach scale, it is seen that the operational duty-cycle of the scales isincreased. That is, by having two storage cups associated with eachscale, for example, the scales will typically be used twice asfrequently for weighing and loading the storage cups as would otherwisebe the case. Further, for a given number of storage cups to be utilizedin a combination weighing system, the present invention is seen torequire half the number of weighing systems as the prior art, thusproviding a substantial reduction in cost.

Further referring to the mechanical operation of the system, eachscale-hopper is provided with two discharge doors 54 and 56. Assymbolically shown in FIG. 1, a discharge controller 58 controls thedoors of the hoppers and further controls discharge of the storage cups.The discharge controller is further in communication with the controlsystem 44. Accordingly, when the control system 44 determines that aparticular one of hoppers 50 and 52 is empty, controller 58 is directedto open the respective door 54 or 56 of scale hopper 34, if filled. Ifthe hopper is empty, control system 44 directs scale 38 to activate thevibratory feeder to provide product thereto. When it is determined thatthe hopper is filled, controller 58 causes the appropriate door of thehopper to open for discharging the product into the appropriate storagecup. Finally, when a particular storage cup is selected as part of acombination needed to make the product weight, controller 58 causes adoor to open in the selected storage cup for discharging its contents toa chute 60, thereby providing the product to a package filling device62. As previously mentioned, the packing device may be a bag maker whichforms, fills and seals a bag containing the desired weight of theproduct.

Referring once again to dispensing apparatus 12, in the preferredembodiment the conical member 16 is provided with a shallow angle, forexample fifteen degrees. Conical member 16 is further rotated in anoscillatory, back-and-forth motion, in order to dislodge any productwhich may gather at the openings 18 and 20 of drum 14. By dislodgingaccumulated product, the openings are kept open and the product is moreeasily distributed to the conveying or feeding devices 24 and 26.

The oscillatory motion, however, is not symmetrical. That is, apredominant forward direction of rotation is provided, with periodicbackward motion. Such backward motion is provided to the conical memberfor shorter time periods than is the forward motion. A structure forachieving such oscillation is shown in FIG. 1 as including a prime mover64, which may be an electrical motor, having an eccentric output member66. A pivoted arm 68 is driven by the motion of eccentric member 66, andis connected thereto by a linkage 70. Because of the schematic nature ofthe Figure, supports and other details of the prime mover and theproduct distributor are not shown.

Conical member 16 is seen to be mounted on a shaft 72. An electricalclutch 74 intermittently couples and decouples pivot arm 68 to shaft 72for rotating conical member 16. It will thus be appreciated that ifclutch 74 were constantly engaged, conical member 16 would be made tooscillate back and forth in substantially equal increments as eccentricoutput member 66 rotates through its cycle. However, clutch 64 isperiodically disengaged during portions of the motion of arm 68 in aparticular directions. That is, in each counterclockwise motion of arm68, clutch 74 may be disengaged for eighty percent of the time. Thus,the conical member is seen to be driven by arm 68 during its fullclockwise motion, but driven by arm 68 during only twenty percent of thecounterclockwise motion. In such an arrangement, conical member 16 isseen to have a predominantly clockwise rotation. Specifically, theconical member rotates clockwise for a first period of time, followed bycounterclockwise rotation for a predetermined fraction of that time. Anadjustable cam and microswitch arrangement may be provided on the primemover apparatus for varying the time periods of engagement anddisengagement of clutch 74.

Referring now to FIG. 2, one embodiment of control system 44 is shown asincluding a desired weight register 76 for storing the weight of productto be made. Thumbwheel switches may be provided for manually setting thedesired weight register.

Upper and lower limit registers 78 and 80 are provided for comparing thetotal product weight in a selected combination of storage cups with anincremented form of the desired weight, thereby to determine whether theselected combination includes a total weight lying within someacceptable range of the desired weight to be made. Registers 78 and 80thus store increments for addition to (and possible subtraction from)the desired weight signal provided by register 76. These increments areadded to (and subtracted from) the desired weight to provide the upper(and lower) limits of the acceptable range. Addition and subtraction ofthe increment may be performed in registers 78 or 80, or alternativelymay be performed in a separate arithmetic unit (not shown).

In operation, a data converter 82 is clocked by a system clock 84 toread in the weights of product in hoppers 32 . . . 34 as provided byscales 36 . . . 38. At the same time that discharge controller 58 causeshoppers 32 . . . 34 to discharge to the associated storage cups, dataconverter 82 transfers the data input from scales 36 . . . 38 to storagelocations provided for the specific storage cups associated with thevarious scales. The weight information is preferably transferred alongwith transfer of the product from scale-hopper to storage cup.

As previously described, the present invention permits selection of adesired number of storage cups to be used in the combinations tested formaking the desired weight. This objective is achieved by targeting eachof the scales 36 . . . 38 to receive a weight equal to some fraction ofthe desired weight to be made. For example, if the desired weight to bemade is fifteen ounces, and each scale is targeted to receive a weightof five ounces, then combinations of sets of three storage cups aretried to provide some such set having a combined weight within theacceptable limits of the desired weights to be made.

In that regard, a combination storage 86 is provided storing allcombinations of three storage cups, for example, to be tested. Thesignals generated by the stored combinations are used to enablecombinations of gates 88 to 90 to pass the weights of selected ones ofthe storage cups from data converter 82 to an arithmetic unit 92.Arithmetic unit 92 is used to add the signals representing the weightsof the selected combination of storage cups. A signal representing thetotal, or combined, weight of the selected storage cups is provided toupper and lower limit registers 78 and 80 via a connecting path 94. Thetotal weight is compared within upper and lower limit registers 78 and80 against the incremented (or decremented) values of the desired weightto be made. Upon a favorable comparison, the appropriate registersoutput a logic one signal on lins 96 and 98. For upper limit register 78a favorable comparison is determined when the total weight is no greaterthan the incremented desired weight. For lower limit register 80, afavorable comparison is determined when the total weight is no lowerthan the decremented desired weight.

Upon determining that the total weight is within the acceptable limits,i.e, no greater than the incremented desired weight and no less than thedecremented desired weight, and AND gate 100 outputs a signal on line102 to a control circuit 104. Control circuit 104 causes the contents ofthe selected storage cups to be dumped into chute 60 for transfer tofilling device 62, and also causes transmission of appropriate signalsto the scales associated with the dumped storage cups to initiatefeeding of product to the appropriate hoppers. If the hoppers associatedwith the selected storage cups are full (a preferred situation), theappropriate doors of the hoppers are opened to reload the storage cups.Thus, by providing a scale associated hopper, it is seen that thestorage cups may be quickly refilled to enable the quick repetition ofcycles wherein the desired weight is made.

As will be appreciated, such quick repetition is somewhat hampered if aselected combination includes, for example, both storage cups 50 and 52of a particular hopper 34 (shown in FIG. 1). In that event, the filledhopper quickly reloads one of the two storage cups, but an entirefeeding cycle is completed prior to reloading of the second associatedstorage cup.

In one feeding device, 1.25 seconds are typically required to fill andsettle the product in a particular scale hopper. Thus, all suchcombinations of storage cups involving a common hopper includes an emptystorage cup. These combinations typically fail the comparison in thelower limit register 80 for the duration of the fill time. This merelydelays operation of the system.

In order to insure more rapid operation, combinations including morethan one storage cup filled from a single hopper are disfavored. Thebias against such combinations is introduced into combination storage 86by storing combinations of storage cups associated with differinghoppers ahead of the disfavored combinations, so that for each cycle ofoperation it is the favored combinations that are first tested. Such abias is easily introduced into a fixed storage by properly ordering theset of combinations to be tested. A further bias may be introduced,however, in order further to speed operation of the invention. As willbe appreciated, in a machine cycle following a selection of a particularstorage cup, the scale-hopper associated therewith is emptied andundergoes a feeding sequence. If a storage cup associated with thathopper is again chosen during that next machine cycle, the hopper, whichis being refilled at the time, is not in a position for rapidlyreloading the storage cup until conclusion of the feeding sequence.Thus, the combination storage may further bias the combination sequenceby flagging, for one machine cycle, the storage location of anycombination involving a hopper undergoing a feeding sequence during thatmachine cycle. By providing first the unflagged combinations to betested and then the flagged combinations, it is seen that occurrences ofthe undesirable situation referred to above may be reduced, thusenhancing the operating speed of the invention.

Upon finding a combination meeting the desired weight limits, and makingthe weight, control circuit 104 provides a signal to combination storage86 to provide combinations in order again to gates 88 . . . 90 for a newcycle of making the desired weight.

In the event that no combination provided by combination storage 86 andtested in arithmetic unit 92 and registers 78 and 80 falls within theacceptable limits for the desired weight, a cycle counter 106 istriggered, by the combination storage 86 having reached its finalcombination, for example, to change one or both increments used in theupper and lower limit registers 78 and 80. Thus, the upper limit ofacceptable weight may be increased or the lower limit may be decreased.It is understood the weights are increased only by a small incrementeach time so as to avoid any problem of product "giveaway" (increasedweight) or package lightness (decreased weight). In any case, the lowerlimit is not changed to fall below the minimum weight required bygovernmental regulations. It is not necessary, of course, to increaseboth deviations at the same time. If performing a number of cycles withsuccessively broadened deviation ranges is required, control circuit 104triggers cycle counter 106 when a successful combination is found tore-initiate the limits in upper and lower limit registers 78 and 80. Thenext cycle of combination testing and weight comparison is thus madeagainst the initial, narrow acceptable limits. It should also be notedthat broadening of the acceptable weight limits need not be accomplishedin uniform steps. That is, after incrementing the upper limit once ortwice, it might be preferable to determine whether there exists anycombination falling within a substantially increased weight range,rather than to dump the contents of all the storage cups and toreinitiate the machine. Accordingly, the second or third incrementationmay raise the acceptable upper limit by an amount larger than theincrement previously applied thereto.

In accordance with the foregoing description, it is seen that thecontrol system of FIG. 2 triggers the control circuit 104 to dump thecontents of the first combination of storage cups having a total weightwithin the acceptable limits for the desired weight to be made.

In a combination weighing apparatus according to the invention, in whicha plurality of storage cups are preferably used in conjunction with eachscale, the number of available combinations of cups is substantiallyincreased.

To further explain, the number of combinations of N things taken R at atime is given by:

    N!/[(N-R)!×R!]

Thus, in a prior art combination weighing system having eight scalesthere are 56 combinations of three scales at a time. In a combinationweighing system according to the present invention, however, in whichtwo storage cups may be provided for each scale, there are 560combinations of three storage cups at a time. Such a dramatic increasein the number of available combinations provides increased assurancethat a combination will be found having a total product weight withinthe acceptable limits for the desired weight to be made. Alternatively,if 56 combinations suffice, the present invention permits the generationof 56 such combinations by using only four of the scale devices, ratherthan 8 as required in the prior art.

In the preferred embodiment of the invention, control system 44 iscomprised of a programmed microprocessor, including therein a number ofregisters, a storage, an arithmetic unit for addition and comparison,and the like. The microprocessor is preferably connected to communicatewith the various scales, thereby to determine the product weightprovided to each hopper. Additionally, the microprocessor may beprogrammed to generate command signals for the scales to activate anddeactivate the product conveying devices. Still further, themicroprocessor may communicate with discharge controller 58 thereby todetermine whether particular hoppers are full or empty, as well as todetect which storage cups are empty. The microprocessor may furthergenerate control signals causing controller 58 to open the appropriatehopper door, and to discharge a selected storage cup into chute 60.Finally, the microprocessor may communicate with, and control, thefilling device 62 to operate upon discharge of a selected combination ofstorage cups thereto.

A microprocessor used to control the present invention as abovedescribed operates in accordance with a particular program providedtherefor. One such program is illustrated by the flow chart of FIG. 3,in which step 201 indicates the initial powering of the system. At step202 operation of the electronic hardware is verified by turning on adisplay and by sensing inputs from a number of switches. Faulty computercomponents may be tested at this step. System initialization isconducted at step 203, and initialization of the weighing apparatus isbegun at step 204.

In this step, all scales and storage cups are emptied, and all inputsand outputs are reset to a known initial condition. At step 205individual preset target weights for the various scales are obtained, aswell as the total product weight to be made.

In step 206 the product feeding devices are initiated, and the scalesprovide the target weights of the product to the individual hoppers andstorage cups associated therewith.

The main operating loop of the system begins at step 207. Duringoperation of the loop, interrupt processing may occur at any point.Interrupts may be provided by any of the scales, for example, toindicate a final determination of product weight received from theproduct conveying devices. In the event that a scale interrupt isreceived at step 208, the weight reading is obtained from the scale atstep 209, and the status of the hopper and storage cups loaded therebyis updated at step 210 to indicate appropriately an empty or a fullstatus. Upon conclusion of the interrupt servicing subroutine at step210, the microprocessor is programmed to establish the acceptable upperand lower limits for the product quantity to be weighed. Such limits areeseablished at step 211.

At step 212 the microprocessor is programmed to access all combinationsof three storage cups, for example. Such combinations may be stored in aregister or other memory associated therewith. The microprocessor maythus access sequential storage addresses having the individualcombinations stored therein. Each location in storage may be addressed,and the contents of that location read out to provide a combination ofweights from predetermined storage cups. The combinations may beidentified by the storage cup reference numbers, or alternatively mayidentify storage locations in which the individual storage cup weightsare stored.

In either case, the product weight in the storage cups identified by thecombination selected in step 212 are summed and repeatedly comparedagainst the upper and lower limits. At step 213 it is determined whethera good combination has been found. When the determination is in theaffirmative, it is further determined at step 215 whether the productmay be filled in the packaging machine. Such a determination is madedepending upon status signals, busy signals and the like which may becommunicated between filling device 62 and the microprocessor. If thefilling device is busy, the microprocessor loops repeatedly untilfilling may be accomplished.

If a determination is made at step 213 that none of the possiblecombinations satisfies the acceptable limits, the limits are relaxed atstep 214 by appropriately incrementing registers or other storagelocations in which the upper and lower limits are stored. The programthen loops back to perform step 212 again, in which all the possiblecombinations of storage cups are again tested for the acceptable weight.

As described, upon determining that the product may be loaded by fillingdevice 62, the microprocessor proceeds from step 215 to step 216 whereincontrol signals are generated for filling the package or container withproduct and for sealing the package. Additionally, the next package forfilling is prepared.

The total weight loaded into the package is caused by the microprocessorto be displayed at step 217. Optionally, the scales used to make thedesired weight are also caused to be displayed by the microprocessor atthat step.

Finally, any operator inputs are detected and serviced at step 218, fromwhich the microprocessor is instructed to return to the beginning of themain loop for the system at step 207.

With respect to step 205, the following observations are noted. If allof the scales in a multiplescale weighing system have mean weightoutputs which are exactly the same, and if a particular number, e.g. 3,of these scales are combined to make up the final desired weight, thenthe mean combined weight will be three times the mean of the individualscale weights. Accordingly, the mean of the output weight cannot be heldany closer to the desired weight than the mean of the individual scales.Similarly, should the mean of the individual scales drift up or down,the mean of the final output weights similarly drifts up or down by thesame amount. Moreover, for all under-weight combinations there must becorresponding over-weight combinations, and vice versa. If acceptableweight limits are broadened only by providing for acceptance ofincreasingly over-weight combinations (legal restrictions, for example,prohibiting the acceptance of under-weight combinations), then anincreasing number of storage cups ultimately store underweight portionsof the total desired weight which may not be useable in any combination.

According to the present invention, this problem may be overcome byoffsetting the target weights for one or more of the scales to be higherthan the input mean (e.g., desired weight divided by three), and tooffset the target weights for one or more scales to be lower than theinput mean. When this approach is taken, the output is no longer rigidlyrelated to the input. By choosing the offset high scales morefrequently, the output mean weight may be raised. Similarly, by choosingthe offset low scales more frequently, the output mean weight may belowered.

Although the target mean weights for various scales may be staggered, anexperimental computer simulation of the results indicates that suchstaggering is unnecessary. Accordingly, the preferred embodimentprovides for all scales receiving a positively displaced offset targetmean weight to receive substantially the same target mean weight, andfor all scales receiving negatively displaced target mean weights toreceive a common target mean weight as well.

By providing the variation and target mean weights, the selectionprocess for choosing acceptable combinations automatically uses the highor low scales as required. No additional costly programming or hardwareis thus needed, nor is any such additional expense desirable to overcomethe problem herein above described.

Referring once again to FIG. 1, a further advantage of the presentinvention is noted with respect to the arrangement of the scale hoppersand associated storage cups, illustrated by hopper 34 and storage cups50 and 52, for example. In order to discharge the product from hopper 34into more than one storage cup, conventional diversion of the product tothe appropriate storage cup typically uses a moveable diverter, whichmay comprise a pivoted vertical plate between the hopper and the twostorage cups. This approach, however, requires vertical displacementbetween the hopper and cups. Such vertical displacement may beincompatible with available overhead clearance, and may further causedamage to the product which must fall through a greater verticaldistance. It is accordingly an advantage of the present invention thatno such vertical displacement is necessary. As previously described,discharge doors 45 and 56 are used to discharge the product from thehopper to the storage cups. Accordingly, the storage cups may be locatedimmediately below the hopper.

There has thus been described a multiple scale combination weighingsystem in which a product is delivered to each scale by a feeder whichis responsive to the scale. As soon as a preset, targeted, productweight is received by the scale, the product feeding device operation isterminated. After a short pause to permit stabilization of the scale,the scale is interrogated in order to determine the true weight of theproduct in its hopper. The weight of the product in the scale is stored,and when an empty storage cup is available, the product is dischargedfrom the scale hopper to the storage cup and the appropriate productweight transferred to a storage location associated with the storage cupreceiving the product.

The inventive system provides for summing of the weight of product invarious selected combinations of storage cups to determine whether thesum weight falls within a preset acceptable range about the desiredweight to be made. The first combination to fall within these limits isselected, the storage cups dumped and a container loaded and sealed. Ifno acceptable combination is found, then one or both of the limits isbroadened and the process repeated. The scales are provided withparticular target weights to assure that combinations of only aparticular number of storage cups need to be tested to make the desiredweight. Some of the scales are provided with target weights higher thanthis value, and some provided with target weights lower than this value.More efficient and less expensive operation is assured by providing aplurality of storage cups for the various scales. Efficient feeding ofproduct is insured by providing a conical member rotating within adistributor for dispensing the product through a plurality of openingssituated about the periphery to corresponding product conveying devices.Apparatus is further provided for rotating the conical member in anoscillating motion, in which the forward or feed direction of motionpredominates over the other.

The foregoing description of a preferred embodiment of the invention ispresented for purposes of illustrations and description, and is notintended to be exhaustive or to limit the invention to the precise formdisclosed, since many modifications and variations are possible in lightof the above teaching. The embodiment was chosen and described in orderto best explain the principles of the invention and its practicalapplication, thereby to enable others skilled in the art to utilize theinvention in various embodiments and with various modifications as aresuited to the particular use contemplated. All such modifications andvariations are within the scope of the invention as determined by theappended claims when interpreted in accordance with the breadth to whichthey are fairly, legally, and equitably entitled.

We claim:
 1. A method for making up a desired weight of a solid flowingproduct as a combination of contents of a predetermined number ofstorage cups comprising the steps of:(a) establishing acceptable upperand lower limits for an acceptable range of product weight to beachieved; (b) distributing quantities of the product to a plurality ofscale hoppers; (c) terminating the distribution of the product to eachhopper in accordance with a determination by the scale associatedtherewith that a predetermined weight has been distributed thereto; (d)feeding the product from each hopper to a storage cup associated withthat particular hopper; (e) registering the weight of product stored ineach of the storage cups of the system; (f) calculating the total weightof successive combinations of the registered product weights of saidpredetermined number of storage cups; and (g) making the desired weightby selecting a combination of storage cups having a total product weightwithin the estalished acceptable limits.
 2. The method of claim 1wherein said step of making the desired weight comprises the step ofselecting the first combination of storage cups having a total weightwithin the established acceptable limits.
 3. The method of claim 2further comprising the step of ordering successive combinations ofstorage cups whose weights are to be totalled in a sequence having acombination of storage cups fed from hoppers of different scales aheadof combinations including plural storage cups fed from a hopper of asingle scale, whereby combinations of storage cups fed from differentscales are favored over combinations including storage cups fed from asingle scale.
 4. The method of claim 3 further comprising the step ofordering successive combinations of storage cups fed from hoppers ofscales not used in making the desired weight in an immediately procedingapplication of the method ahead of combinations including storage cupsfed from hoppers of scales used in making the desired weight in animmediately preceding application of the method, whereby combination ofstorage cups fed from scales not used in making the desired weight in animmediately preceding application of the method are favored overcombinations of storage cups fed from hoppers of scales used in makingthe desired weight in an immediately preceding application of themethod.
 5. The method of claim 2 further comprising the step ofestablishing a target mean weight for the product to be distributed toeach of the scale-hoppers as a first fraction having a denominatordetermined by the predetermined number of storage cups to be used inmaking up a combination and a numerator determined by the desiredproduct weight.
 6. The method of claim 5 wherein said step ofestablishing a target mean weight comprises the further steps ofproducing second and third fractions having values offset above andbelow said first fraction and providing said second and third fractionsto several of the scale-hoppers, thereby targeting some of the scalehoppers to receive quantities of the product having a mean weight abovethe first fraction and others of the scale-hoppers to receive quantitiesof the product having a mean weight below the first fraction.
 7. Themethod of claim 1 further comprising the steps of:(a) determining theoccurrence of a situation wherein none of the combinations of productweight have a total weight within the established acceptable limits; (b)broadening the acceptable range of product weights to be achived bychanging at least one of the acceptable limits; (c) making the desiredweight by selecting a combination of storage cups having a total productweight within the changed acceptable limits; and (d) repeating steps a,b and c until a combination of storage cups is found having a totalproduct weight within some acceptable broadened range therefor.
 8. Themethod of claim 7 wherein said broadening step comprises the step ofreducing the lower limit of the acceptable range.
 9. The method of claim7 wherein said broadening step comprises the step of raising the upperlimit of the acceptable range.
 10. The method of claim 7 whereinsuccessive iterations of said broadening step within said repeating stepinclude the steps of changing the acceptable limits by successivelygreater increments.
 11. The method of claim 7 further comprising thesteps of filling the product into a container when a combination isselected making the desired weight within the acceptable limits.
 12. Themethod of claim 7 wherein said step of making the desired weight byselecting a combination of storage cups comprises the further steps ofdetermining an address in a storage, reading the combination from astorage location at the address, and incrementing an address pointer toa subsequent location.
 13. Apparatus for making up a desired weight of asolid flowing product as a combination of contents of a predeterminednumber of storage cups comprising:means for distributing quantities ofthe product to a plurality of scale hoppers; scale means for providing apredetermined weighed quantity of the product to a hopper associatedtherewith; at least one storage cup associated with each of said hoppersfor receiving the product therefrom; and a control systemincluding:means for establishing acceptable upper and lower limits foran acceptable range of product weights to be achieved; means forregistering the weight of product stored in each of the storage cups inthe system; means for calculating the total product weight in aparticular combination of said predetermined number of storage cups;means for providing successive combinations of storage cups to saidmeans for calculating the total product weight; and selecting meansreceiving the calculated total product weight in combinations of storagecups and further receiving the upper and lower limits for the acceptablerange of product weight from said means for establishing, for selectingthe first combination of storage cups having a combined product weightfalling within the established upper and lower weight limits for makingthe desired weight, said selecting means providing a first signal tosaid means for providing combinations, for providing new combinations tosaid calculating means for making the next desired weight afterselecting a combination.
 14. Apparatus as recited in claim 13 furthercomprising means for dumping product from the selected combination ofstorage cups to a container therefor and for reloading the emptiedstorage cups, responsive to an output signal from said selecting means.15. Apparatus as recited in claim 13 wherein said control system furthercomprises cycling means, responsive to said means for generatingsuccessive combinations for providing a second signal to said means forestablishing, the second signal indicative of a failure of allcombinations of storage cups to provide a weight falling within theestablished upper and lower limits, said means for establishingincluding means responsive to said second signal for broadening theacceptable range of product weight to be achieved.
 16. Apparatus asrecited in claim 15 wherein said means for broadening includes means forreducing the lower limit of the acceptable range.
 17. Apparatus asrecited in claim 15 wherein said means for broadening includes means forraising the upper limit of the acceptable range.
 18. Apparatus asrecited in claim 15 wherein said means for broadening includes means forincreasing the acceptable range of product weight by successivelygreater increments for successive cycles.
 19. Apparatus as recited inclaim 13 wherein said control system comprises a programmedmicroprocessor which forms the establishing, registering, calculating,providing, and selecting means, and which further includes dividingmeans for forming a first fraction, having a denominator determined bythe predetermined number of storage cups to be used in the combinationand a numerator determined by the desired product weight, the firstfraction provided to the scale means as a target mean weight to beprovided to the hopper associated therewith.
 20. Apparatus as recited inclaim 19 wherein said control system includes means for varying thefraction formed by the dividing means, thereby providing second andthird fractions having values offset above and below said first fractionto several of said scale means, whereby some of said scale means aretargeted to receive quantities of the product having a mean weight abovethe first fraction, and others of said scale means are targeted toreceive quantities of the product having a mean weight below the firstfraction.
 21. Apparatus as recited in claim 13 wherein said means fordistributing includes structure for receiving the product, including adistributor having a cavity and an opening for receiving the product,rotating means within the distributor for dispensing the product to eachof the scale hoppers, andcontrol means for alternately causing saidrotating means to rotate in a first direction and in a second, opposite,direction for dislodging jams of the product.
 22. Apparatus as recitedin claim 21 wherein said control means includes motive means forrotating said rotating means for a greater period of time in said firstdirection than in said second direction.
 23. Apparatus as recited inclaim 22 wherein said motive means includes an eccentric prime mover, apivoted arm connected to said rotating means, and linkage meansconnecting said prime mover to said pivoted arm, further including aclutch means for selectively engaging and disengaging said pivoted armfrom a shaft connected for rotating said rotating means.
 24. Apparatusfor dispensing a solid flowing product to a plurality of receiverscomprising:a distributor having a cavity and an opening for receivingthe product, a rotating means within the cavity for dispensing theproduct through a plurality of openings in the distributor to theplurality of receivers therefor, and control means for alternatelycausing said rotating means to rotate in a first direction and in asecond, opposite direction.
 25. Apparatus as recited in claim 24 whereinsaid control means includes motive means for rotating said rotatingmeans for a greater period of time in said first direction than in saidsecond direction.
 26. Apparatus as recited in claim 25 wherein saidmotive means includes an eccentric prime mover, a pivoted arm connectedto said rotating means, and a linkage means connecting said prime moverto said pivoted arm, further including a clutch means for selectivelyengaging and disengaging said pivoted arm from a shaft connected forrotating said rotating means.